Owing to their simple nature and number of practical applications, the adsorption of halomethanes onto various substrates has been a topic of study in materials science for a number of years. While a number of studies have reported on the surface characteristics of halomethane adsorption on simple, neutral substrates such as graphite, less well understood in general is the behavior of similar adsorbates on other, possibly widely different substrates. How the choice of substrate affects the manner in which these compounds are adsorbed as well as the effects of the substrate on the structure of the adsorbate more than a monolayer thick is less understood. In this presentation, we report the results of a recent molecular dynamics study comparing the structure and dynamics of systems composed separately of three tetra substituted halomethanes - CF4, CF3Cl, and CF3Br - adsorbed onto two different substrates - graphite and silica (alpha-quartz) - along a range of temperatures to examine how these systems evolve and change according to the characteristics of the substrate surface.